The present invention relates generally to the administration of fluid to a patient or to the withdrawal of fluid from a patient and relates more specifically to a method and system for controllably administering fluid to a patient and/or for controllably withdrawing fluid from the patient.
There are many situations in which it may be desirable to administer one or more fluids to a patient or to withdraw one or more fluids from a patient. An example of one such situation involves the administration of regional anesthesia to a patient. In contrast to general anesthesia, which is a systemic sedation of a patient, regional anesthesia is the administration of medication to specific body regions by anesthetizing specific nerves, thereby permitting the patient to block pain and to be cognitively alert or conscious. Regional anesthesia may be used to treat pain during surgery and during post-surgery recovery and may also be used to provide patients with extended relief of longer-term pain. Because regional anesthesia is not systemic, regional anesthesia increase patient safety and satisfaction and, concurrently, reduces anesthesia cost. Regional anesthesia is an effective technique for selectively anesthetizing a specific region of the body without interfering with a patient's vital systems.
Traditionally, regional anesthesia involves the use of a specialty regional anesthesia needle, which the physician uses to infuse medication in close proximity to the target nerves to be blocked, i.e., anesthetized. The physician may insert the needle blindly, using anatomical landmarks of the patient in an attempt to locate the nerve to be blocked. If the needle tip is more than 5 mm from the nerve, the anesthesia may be ineffective. If the needle tip touches the nerve, such contact of the nerve by the needle tip may cause nerve damage. With effective manual needle insertion and infusion, the patient experiences paresthesia, a buzzing tingling sensation, which is usually orally reported by the patient to the physician.
As can be appreciated, the success rate of a blindly-located nerve block is lowered if the patient's feedback to the physician during the needle insertion procedure is inaccurate or if the patient is disoriented or unresponsive. To minimize the likelihood of an errant positioning of the infusion needle, certain devices have been used to help position the needle in proximity to the body portion that one wishes to target. One such device is a nerve stimulator, which provides electrical current to the infusion needle and which causes a body portion contacted by the needle to twitch, thereby providing a visual indicator to the physician of the location of the needle. Examples of nerve stimulators are disclosed in the following documents, all of which are incorporated herein by reference: U.S. Pat. No. 5,284,153, inventors Raymond et al., issued Feb. 8, 1994; U.S. Patent Application Publication No. US 2007/0213771 A1, inventors Spinner et al., published Sep. 13, 2007; U.S. Patent Application Publication No. US 2004/0059247 A1, inventor Urmey, published Mar. 25, 2004; European Patent Application Publication No. EP 0 957 982 A1, published Nov. 24, 1999; and European Patent Application Publication No. EP 0 637 934 A1, published Feb. 15, 1995.
Another device that is commonly used, either in place of a nerve stimulator or in combination therewith, to help position in infusion needle in proximity to a body portion that one wishes to target is a handheld ultrasonic imager. Examples of handheld ultrasonic imagers are disclosed in the following documents, all of which are incorporated herein by reference: U.S. Pat. No. 8,257,262 B2, inventors Petersen et al., issued Sep. 4, 2012; U.S. Pat. No. 7,645,238 B2, inventor Hirsch, issued Jan. 12, 2010; and U.S. Patent Application Publication No. US 2007/0073155 A1, inventors Park et al., published Mar. 29, 2007.
One of the shortcomings associated with administering regional anesthesia to a patient in the manner described above is that typically more than one person is needed to perform the procedure. This is because, for example, the physician may use one hand or both hands to position the needle in the patient or may use one hand to position the needle in the patient and may use another hand to hold a handheld ultrasonic imager, a nerve stimulator, or another device used to help locate the needle in the patient. As a result, a nurse or other assistant is typically needed to operate the syringe or other fluid flow device coupled to the infusion needle, typically by a length of tubing, so that the desired quantity of anesthesia may be dispensed through the infusion needle.
In addition, despise the advent of techniques to help position the needle correctly, the needle tip may inadvertently be inserted into a nerve. As can be appreciated, if insertion of the needle tip into a nerve occurs, any subsequent injection of anesthesia into the nerve may cause significant injury to the nerve. Such injury to the nerve can be either mechanical or ischemic trauma due to an increase in endoneural pressure caused by the fluid injected and/or endoneural edema. In view of the above, current recommendations are for the syringe operator to avoid high injection pressures. However, a determination of when an injection pressure is, in fact, dangerously high has traditionally been based simply on a subjective feel of the syringe by the syringe operator, without any accompanying objective measurement of the actual injection pressure. Such a subjective assessment by the syringe operator is further complicated by the differences in hand strength among different users and by the multitude of needle types, needle lengths, and needle lumen calibers, all of which can affect an interpretation of what is too forceful or too fast.
In an attempt to address some, but not all, of the above issues, there is disclosed a method and apparatus to decrease the risk intraneuronal injection during administration of nerve block anesthesia in U.S. Pat. No. 6,866,648 B2, inventors Hadzic et al., issued Mar. 15, 2005, which is incorporated herein by reference. More specifically, the aforementioned patent teaches the provision of a pressure sensing device located between an injection device (typically a syringe) and a nerve block needle whereby injection pressure during a nerve block injection can be easily and objectively monitored, thereby allowing the operator to monitor the injection pressure and/or injection speed during a nerve blockage injection procedure and to take appropriate corrective actions if abnormal pressure conditions are observed.
Other document that may be of interest include the following, all of which are incorporated herein by reference: U.S. Pat. No. 7,727,224 B2, inventor Hadzic et al., issued Jun. 1, 2010; U.S. Pat. No. 7,689,292 B2, inventors Hadzic et al., issued Mar. 30, 2010; U.S. Pat. No. 5,910,135, inventors Hadzic et al., issued Jun. 8, 1999; U.S. Pat. No. 5,830,151, inventors Hadzic et al., issued Nov. 3, 1998; PCT International Publication No. WO 2012/139035 A1, published Oct. 11, 2012; European Patent Application Publication. No. EP 1 599 135 A2, published Nov. 30, 2005; Steinfeldt et al., “Forced Needle Advancement During Needle-Nerve Contact is a Porcine Model: Histological Outcome,” Anesth. Analg., 113:417-20 (2011); ASRA News, May 2009 Newsletter, a Publication of the American Society of Regional Anesthesia and Pain Medicine; Theron et al., “An Animal Model of ‘Syringe Feel’ Daring Peripheral Nerve Block,” Reg. Anesth. Pain Med., 34(4):330-2 (2009); Robards et al., “Intraneural Injection with Low-Current Stimulation During Popliteal Sciatic Nerve Block,” Anesth Analog., 109:673-7 (2009); Gerancher et al., “Development of a Standardized Peripheral Nerve Block Procedure Note Form,” Reg. Anesth. Pain Med., 30(1):67-71 (2005); Claudio et al., “Injection Pressures by Anesthesiologist During Simulated Peripheral Nerve Block,” Reg. Anesth. Pain Med., 29(3):201-5 (2004); Hadzic et al., “Combination of Intraneural Injection and High Injection Pressure Leads to Fascicular Injury and Neurologic Deficit in Dogs,” Reg. Anesth. Pain Med., 29(5):417-23 (2004); Auroy et al., “Major Complications of Regional Anesthesia in France,” Anesthesiology, 97:1274-80 (2002); Urmey et al., “Inability to Consistently Elicit a Motor Response following Sensory Paresthesia during Interscalene Block Administration,” Anesthesiology, 96:552-4 (2002); Borgeat et al., “Evaluation of the Lateral Modified Approach for Continuous Interscalene Block after Shoulder Surgery,” Anesthesiology. 99:436-42 (2003); and ASRA News, May 2007 Newsletter, a Publication of the Americas Society of Regional Anesthesia and Pain Medicine.